The parahippocampal gyrus (Syn. hippocampal gyrus) is a grey matter

Grey matter

Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil , glial cells and capillaries. Grey matter contains neural cell bodies, in contrast to white matter, which does not and mostly contains myelinated axon tracts...

 cortical

Cerebral cortex

The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...

 region of the brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

 that surrounds the hippocampus

Hippocampus

The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

. This region plays an important role in memory

Memory

In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....

 encoding

Encoding (Memory)

Memory has the ability to encode, store and recall information. Memories give an organism the capability to learn and adapt from previous experiences as well as build relationships. Encoding allows the perceived item of use or interest to be converted into a construct that can be stored within the...

 and retrieval.

It has been involved in some cases of hippocampal sclerosis.

Asymmetry has been observed in schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

.

Divisions

The anterior part of the gyrus includes the perirhinal

Perirhinal cortex

Perirhinal cortex is a cortical region in the medial temporal lobe that is made up of Brodmann areas 35 and 36. In rats, it is located along and dorsal to the rhinal sulcus. It receives highly-processed sensory information from all sensory regions, and is generally accepted to be an important...

 and entorhinal cortices.

The term parahippocampal cortex is used to refer to an area that encompasses both the posterior parahippocampal gyrus

Posterior parahippocampal gyrus

The posterior parahippocampal gyrus is a portion of the parahippocampal gyrus.It can show deterioration in Alzheimer's disease....

 and the medial portion of the fusiform gyrus

Fusiform gyrus

The fusiform gyrus is part of the temporal lobe in Brodmann Area 37. It is also known as the occipitotemporal gyrus. Other sources have the fusiform gyrus above the occipitotemporal gyrus and underneath the parahippocampal gyrus....

.

Scene recognition

The parahippocampal place area (PPA) is a subregion of the parahippocampal cortex that plays an important role in the encoding and recognition of scenes (rather than faces or objects). fMRI studies indicate that this region of the brain becomes highly active when human subjects view topographical scene stimuli such as images of landscapes, cityscapes, or rooms (i.e. images of "places"). The region was first described by Russell Epstein (currently at the University of Pennsylvania) and Nancy Kanwisher

Nancy Kanwisher

Nancy Kanwisher is a Professor in the McGovern Institute for Brain Research at MIT. She studies the neural and cognitive mechanisms underlying human visual perception and cognition. Her work investigates object recognition, visual attention, and perceptual awareness, as well as response selection,...

 (currently at MIT) in 1998, see also other similar reports by Geoffrey Aguirre and Alumit Ishai.

Damage to the PPA (for example, due to stroke) often leads to a syndrome in which patients cannot visually recognize scenes even though they can recognize the individual objects in the scenes (such as people, furniture, etc.). The PPA is often considered the complement of the fusiform face area

Fusiform face area

The fusiform face area is a part of the human visual system which might be specialized for facial recognition, although there is some evidence that it also processes categorical information about other objects, particularly familiar ones.-Localization:...

(FFA), a nearby cortical region that responds strongly whenever faces are viewed, and which is believed to be important for face recognition.

Social context

Additional research has increased the probability that the right parahippocampal gyrus in particular has functions beyond the contextualizing of visual background. Tests by a California-based group led by Katherine P. Rankin indicate that the lobe may play a crucial role in identifying social context as well, including paralinguistic elements of verbal communication. For example, Rankin's research suggests that the right parahippocampal gyrus enables people to detect sarcasm.

External links

• http://www2.umdnj.edu/~neuro/studyaid/Practical2000/Q35.htm
• Temporal-lobe.com An interactive diagram of the rat parahippocampal-hippocampal region